Automatic reclosing circuit-breaker system



May 12, 1925. 1,537,727

A. E. ANDERSON AUTOMATIC REC/LOSING CIRCUIT BREAKER SYSTEM Filed May 24,1924 Inventor- I AT'Vid B. Anderson,

His Attorney.

Patented May 12, 1925.

UNITED STATES 1,537,721 PATENT OFFICE.

ARVID E. ANDERSON, OF SCOTIA, NEW YORK, ASSIGNOR T0 GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW'YOBK.

AUTOMATIC RECLOSING CIRCUIT-BREAKER SYSTEM.

Application filed May 24,

To all whom it'ma'z concern:

Be it known that I, ARVID E. ANDERSON, a citizen of the United States,residing at Scotia, in the county of Schenectady, State of New York,have invented certain new and useful Improvements in Automatic ReclosinCircuit-Breaker Systems, of which the to lowing is a specification.

My invention relates to automatic reclosing circuit breaker systems.

In accordance with one of the automatic reclosing circuit breakersystems which is in extensive use at the present time, a circuit breakeris arranged to be reclosed automatically after it has been opened by anoverload and has remained open for a certain length of time. If theoverload is still present when the circuit breaker is reclosed thecircuit breaker again opens and the above cycle of operation is repeateda predetermined number of times after which the automatic reclosingsystem is rendered inoperative. If at any time, while the automaticreclosing system is operative, the overload disappears, the circuitbreaker remains closed when reclosed. In some cases the reclosing systemis also arranged to be rendered inoperative in case of an excessiveoverload or short circuit, since the circuit breaker and other apparatusmay be seriously damaged by opening and closing a circuit breaker undersuch severe abnormal conditions. In arrangements which have been usedheretofore for accomplishing this result it has been necessary for theoperator or some other person to release certain switches or relays inorder to render the automatic reclosing system; operative again tocontrol the reclosing of the circuit. Therefore it is evident that incases where continuity of service is very desirable these arrangementsare not entirely satisfactory because the circuit breaker may remainopen longer than is necessary so far as the load conditions areconcerned.

One object of my invention is to provide an automatic reclosing circuitbreaker system in which the automatic reclosing means is renderedinoperative to reclosethe circuit breaker when the abnormal condition exceeds a predetermined value and the automatic reclosing means isrendered operative again to .close the circuit breaker when the abnormalcondition has disappeared.

My invention will be better understood 1924. Serial No. 715,726.

from the following description when taken n connection with theaccompanying draw- 1ng, which diagrammatically shows an automaticreclosing circuit breaker system embodying my invention, and its scopewill be pointed out in the appended claims.

Referring to the drawing, 1 represents a source of current shown as agenerator, which is arranged to be connected to a load circuit 2, bymeans of a circuit breaker 3 of any well known type. The load circuit 2is also arranged to be supplied by one or more other sources 1'.

In order to simplify the drawing, it is assumed that the ground is oneside of the load circuit. One terminal of the generator 1 is showndirectly connected to ground and the circuit breaker 3 is arranged toconnect the other terminal to the metallic conductor of the loadcircuit. It is evident, however, that my invention is neither limited toa grounded system nor to having the circuit breaker 3 control theconnector between only one terminal of the generator and thecorresponding side of the load circuit.

As shown, the circuit breaker 3 is of the well known latched-in typehaving a closing coil 4 which, when energized, closes the circuitbreaker, and a trip coil 5 which, when energized releases the latch 6that holds the circuit breaker in its closed position. The trip coil 5is arranged to be connected across a suitable source, such as thegenerator 1, by means of an overload relay 7 when the current suppliedby the generator 1 exceeds a predetermined value.

For automatically reclosing the circuit breaker 3 after the circuitbreaker opens in response to an overload, which does not exceed apredetermined amount, I provide a reclosing relay 8, which is arrangedto be energized after the circuit breaker opens and which, after apredetermined time, completes the circuit of the hesitating controlrelay 9, which in turn completes the circuit of the closing coil 4 toclose the circuit breaker.

Each time the circuit breaker 3 opens a notching relay 10 is energized.This relay is arranged to open the circuit of the reclosing relay 8,after the circuit breaker has been opened a predetermined number of,times. The contacts of the notching relay are preferably arranged sothat they can be reset only by hand so that when they are opened by thenotching relay the reclosing relay 8 is rendered inoperativeto reclosethe circuit breaker.

Relay 11 is an auxiliary relay for the c1rcuit breaker which operateswhen the circuit breaker 3 opens, to efiect the operation of certainother relays of the system in a manner hereinafter described.

In order to prevent the reclosingrelay 8 from operating to close thecircuit breaker 3 after an excessive overload or short circuit hasoccurred, a lockout relay 12 isprovided, the circuit of which isarranged to be completed by means of a second overload relay 14 which isset to operate in response to a higher value of current than theoverload relay 7. The lockout relay 12 is arranged in any well knownmanner so that after the coil of the relay 12 has been energized toprevent the operation ofthe reclosing relay 8, the subsequentdeenergi'zation of the relay 12 does not render the reclosing relay 8again operative. As shown, a latch 13 is provided for holding the relay12 in its energized position.

As shown the overload relays 7 and 14 are connected in series across aresistance shunt in the circuit of the "generator 1 but it is evidentthat the windings may be connected directly in series with thegenerator, or in any other well known manner, so that they are energizedin accordance with the amount of current supplied by the generator 1.tothe load circuit 2.

In order to insure that the lockout relay 12 has time to operate beforethe circuit breaker 3 opens, the overload relays 7 and 14 are preferablyarranged so that the relay 14 operates to effect the operation of thelockout relay 12 before the relay 7 eifects the opening of the circuitbreaker. This may be accomplished in any well known manner as by makingthe overload relay 14 a substantially instantaneous relay and the relay7 a time relay.

In order to render the reclosing relay 8 operative to reclose thecircuit breaker 3 after the lockout relay 12 has been ener ized and theexcessive overload, which cause the relay 12 to be operated, hasdisappeared I provide a relay 16 which is connected across the loadcircuit and which is arranged to complete the circuit of a releasemagnet17 to release the latch 13 of the lockout relay 12 when the voltageacross the load circuit exceeds a predetermined value. It will beevident that in case of a short circuit or an excessive overload thevoltage across the load circuit, due to the load circuit being energizedat some other point, is low. When, however, the short circuit orexcessive overload has disappeared, substantially normal voltage isrestored so that the volt-l age across the load circuit isan indicationof the condition of the load circuit. Therefore by setting the rela 16so that it operates to release the late 13 of the lookout relay 12 whenthe voltage across the load circuit is above a predetermined value, theautomatic reclosing system is rendered operative to control the reclosinof the circuit breaker when the severe a normal condition hasdisappeared.

The operation of the system shown is as follows: When the circuitbreaker 3 is closed and the load conditions are normal so that neitherone of the overload relays 7 and 14 is sufiiciently energized to close1ts contacts, the circuit breaker is held in its closed osition by thelatch 6 and the apparatus is in the osition shown in the drawing.

hen an overload occurs, the overload relay 7 operates with a time relaydelay to close its contacts 20. If the overload is severe enough theoverload relay 14 also operates and closes its contacts 21. Asheretofore described, the relay 14 is preferably arranged so that itoperates more quickly than the relay 7 in order that the contacts 21 maybe closed before the contacts 20 in case of a severe overload.

It will first be assumed that an overload occurs which causes the relay7 to operate but does not cause the relay 14 to operate. The closing ofthe contacts 20 of the overload relay 7 completes a circuit for the tripcoil 5 to trip open the circuit breaker 3. This circuit is from theungrounded terminal of the generator 1 through-the trip coil 5,auxiliary contacts 22 on the circuit breaker, which are closed when thecircuit breaker is closed, conductor 23, contacts 20 of the overloadrelay 7 to the ground.

When the circuit breaker 3 opens, the opening of its auxiliary contacts24 opens the circuit of the auxiliary relay 11 which is connected acrossthe generator 1 when the circuit breaker is closed. The rela 11, whendeenergized, closed three sets 0 contacts 26, 27 and 28.

The closing of the contacts 26 connects the relay 16 across the loadcircuit 2. If the voltage across the load circuit 2 is above apredetermined value the relay 16 closes its contacts 29 and completes acircuit from the ungrounded terminal of the generator 1 through thecontacts 29 of the relay 16, resistor 30, conductor 31, contacts 32 and33 of the lockout relay 12, conductor 34, contacts 27 of the relay 11 toground. The release coil 17 of the lockout relay 12 is connected acrossthe conductors 31 and 34, but since the overload is assumed not to besevere enough to operate the lookout relay, the contacts 32 and 33,which are arranged to connect the conductors 31 and 34 directly toether, short circuit the release coil 17. I the voltage across the loadcircuit is not high enough to operate the relay 16 after the circuitbreaker 3 opens, the

above described circuit remains open. It will be evident from thefollowing description that when only the overloa relay 7 is operated,the rela 16 has noefi'ect u on the operation of t e automat1c reclosingsystem so that the circuit breaker 3 is reclosed irrespectively of theposition of the relay 16.

The closing of the contacts 27 of the relay 11 completes the circuit ofthe reclosing relay 8 and the notching relay 10. T1115 circuit is fromthe ungrounded terminal of the generator 1 through the contacts of thenotching relay 10, conductor 36, coil of the notching relay 10,conductor 37, 0011 of the reclosing relay 8, conductor 38, contacts 39and 32 of the lockout relay 12, conductor 34, contacts 27 of the relay11 to ground. The reclosing relay 8 is arranged in any suitable manner,as by means of a dash pot 40, so that it does not close its contacts 41until a predetermined time after the coil of the relay is energized.

The notching rela 10 is arranged in any suitable manner so t at it doesnot open its contacts 35 until after the coil of the relay has beenenergized a predetermined number of times. This relay is also preferablyarranged so that the coil of the relay has to be energized successivelya predetermined time with less than a redetermined time betweensuccessive energizations in order to open the contacts 35.

As shown in the drawing, the plunger 43 of the notching relay 10 isarranged to actuate a ratchet 44, against the action of a spring 45, anda time delay device 46 such as a dash pot or a bellows. The rela is alsoprovided with a holding pawl 47 w ich is normally held out of engagementwith the ratchet 44 by the weight of the movable element of the timedelay device 46 so that the ratchet can be rotated to its normalposition by the spring 45, and which is arranged to be moved intoengagement with the ratchet 44 by a spring 48 when the time delay device46 is actuated by the plunger 43. The time delay device 46' ispreferably arranged so that only the downward movement of the movableelement thereof is delayed. An arm 49 is attached to the ratchet 44 andis normally held against a stop 50 by the spring 45. When the coil ofthe relay 10 is energized successively a predetermined number of timeswith less than a predetermined time between successive energizationswhich is sufficient to allow the time delay device 46 to return to itsnormal position, the arm 49 o ens the contacts 35 which are arranged toe held in their open position until they are manually reset.

When the above described circuit for the coils of the notchin relay 10and the reclosing relay 7 is c osed, the energization of the coil of thenotching relay 10 moves the ratchet 44 the distance of one tooth andmoves upward the movable element of the time delay device 46. The spring48 then moves the holding pawl 47 into engagement with the ratchet 44 sothat the ratchet is held in its actuated position after the coil of therelay is deener ized.

After the circuit 0 the coil of the reclosing relay 8 has remainedclosed for a certain length of time, the relay 8 closes its contacts 41and completes the circuit of the hesitating control relay 9. Thiscircuit is from the ungrounded terminal of the generator 1, through thecoil of the relay 9, conductor 52, contacts 41 of the reclosing relay 8,conductor 53, contacts 28 of the relay 11 to ground. The hesitatingcontrol relay, by closing its contacts 54, connects the closing coil 4of the circuit breaker directly across the generator 1.

The energization of the closing coil 4 closes the circuit breaker 3 andif the overload has disappeared, the circuit breaker remains in itsclosed position. The closing of the circuit breaker completesthe circuitof the auxiliary relay 11 which opens its three sets of contacts 26, 27and 28. The opening of these three sets of contacts deenergizes therelays 8, 9, 10 and 16 which return to their normal positions. Thehesitating control relay 9, however, is arranged in any well knownmanner'so that it does not open its contacts 54 until after the coil ofthe relay 9 has been deenergized for a certain length of time. In thismanner it is insured that the circuit of the closing coil 4 remainsenergized for a suflicient length of time to close the circuit breaker.

If the overload is still connected to the load circuit 2 when thecircuit breaker 3 is reclosed, the overload relay 7 operates again andthe above cycle is repeated except that the notching relay 10 is movedthe distance of another tooth each time the circuit breaker opens. Ifthe overload does not disappear, this cycle is repeated a predeterminednumber of times after which the notching relay 10 opens its contacts 35which are in the circuit of the reclosing relay 8. Since the cont-acts35 have to be reset by hand, further automatic reclosin of the circuitbreaker is prevented unti these contacts are reset by the operator orsome other person.

It will now be assumed that the overload that causes the overload relay7 to close its contacts is also severe enou h to cause the overloadrelay 14 to close its contacts 21. The overload relay 7 eflects theopening of the circuit breaker 3 in the manner heretofore described, butbefore this occurs, the closing of the contacts 21 completes a circuitfor the coil of the lookout relay 12.

This circuit is from the ungrounded terminal of the generator 1 throughthe auxiliary contacts 24 on the circuit breaker 3,

conductor 57, coil of the lockout relay 12,

conductor 58, contacts 21 of the overload relay 14 to ground, Since thelockout relay 12 is held in its energized position by the latch 13, thesubsequent deenergization of the coil of the relay 12, when the circuitbreaker opens,'does not cause the relay to reclose its contacts 32, 33and 39. Since the contacts 39 and 32 are in the circuit of the reclosingrelay 8, it is evident that so long as the lookout relay 12 is held inits energized osition the automatic reclosing system is inoperative toreclose the circuit breaker.

The lockout relay 12 remains in its energized position until the relay16, which is connected across the load circuit by contacts 26 of therelay 11 after the circuit breaker opens, is sufficiently energized toclose its contacts 29. The relay 16 is preferably set so that itoperates only when the voltage across the load circuit is substanentstatutes, shown and described my invention as applied to a particularsystem and as embodying various devices diagrammatically indicated,changes and modifications will be obvious to those skilled in the artand I, therefore, aim in the appendedclaims to cover all such variationsand modifications as fall Within the true spirit and scope of myinvention.

\Vhat I claim as new and desire to secure by Letters Patent of theUnited States, is

1. In an automatic reclosing circuit breaker system, a sourceof'current, a load circuit, a circuit breaker arranged to connect saidsource to said load circuit, means operative when said circuit breakeris open to effect the automatic reclosing of said circuit breaker, meansresponsive to a predetermined overload condition of said load circuitfor rendering said automatic reclosing means inoperative to reclose saidcircuit breaker, and means operative in response to a predeterminedcondition of said load circuit for automatically rendering saidreclosing means operative to reclose said circuit breaker subsequentlyto said reclosing means having been rendered inoperative.

2. In an automatic reclosing circuit breaker system, a source ofcurrent, a load said circuit breaker subsequently to said reclosingmeans having been rendered inoperative.

3, In an automatic reclosing circuit breaker system, a source ofcurrent, a load circuit arranged to be supplied with current at aplurality of points, a circuit breaker arranged to connect said sourceto said load circuit, overload responsive means for effecting theopening of said circuit breaker, means for automatically reclosing saidcircuit breaker after being opened by said overload responsive means,overload responsive means operative in response to a greater overloadthan said first mentioned overload responsive means for rendering saidautomatic reclosing means inoperative, and means responsive to thevoltage of said load circuit for automatically rendering said automaticreclosing means operative after having been rendered inoperative by saidsecond mentioned overload responsive means.

4. In an automatic reclosing circuit breaker system, a. source ofcurrent, a load circuit arranged to be supplied with current at aplurality of points, a circuit breaker arranged to connect said sourceto said load circuit, overload responsive means for etfecting theopening of said circuit breaker. a reclosing relay arranged whenenergized to effect the closing of said circuit breaker, a circuit forsaid relay, means operative in response to the opening of said circuitbreakertocomplete said reclosing relay circuit, a lockout relayoperative to interrupt said reclosing relay circuit upon the occurrenceof a greater overload than is required to operate said overloadresponsive means, and resetting means for said lockout relay controlledby the voltage of said load circuit.

5. In an automatic reclosing circuit breaker system. a source ofcurrent, a load circuit arranged to be supplied with current at aplurality of points, a circuit breaker arranged to connect said sourceto said load circuit, time delayed overload responsive means foreffecting the opening of said cir- "cuit breaker, a. reclosing relayarrangedl when energized to effect the closing of said circuit breaker,a circuit for said relay.

lUO

means operative in response to the opening of said circuit breaker tocomplete said reclosing relay circuit, a relay connected and arranged tointerrupt said reclosing relay circuit upon the occurrence of a greateroverload than isrequired to operate said overload responsive means,means for bolding said relay in its circuit interrupting position, awinding to effect the release of said holding means, and means forconnecting 10 said winding across said load circuit after said circuitbreaker opens.

In witness whereof, I have hereunto set my hand this 23rd day of May,1924.

ARVID E. ANDERSON.

